NASA Technical Reports Server (NTRS) 20110015359: Loads and Structural Dynamics Requirements for Spaceflight Hardware

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by  NASA Technical Reports Server (NTRS)

JSC-65829 was subject to two cycles of review by discipline experts from multiple Agency
centers as part of its development to support the Commercial Crew Transportation Services
Program. Reviews were conducted in April 2010 and over a period spanning July 2010 to
December 2010. Reviewers participating and actively providing comments were:

Eli Rayos (JSC-ES611)
Bob Ryan (MSFC-HS10)[Will Technology Inc - ASRI]
Dave McGhee (MSFC-EV31)
Scott West (JSC-ES611)
Lee Wilson (JSC-ES611)
Vince Fogt (JSC-ES611)
George James (JSC-ES611)
Rodney Rocha (JSC-ES611)
Quyen Jones (JSC-ES611)
George Zupp (JSC-EA) [Jacobs Technology]
Tom Modlin (JSC-ES2) [Barrios]
Isam Yunis (LARC-D206)
Scott Gordon (GSFC-5420)
Teresa Kinney (KSC-NEO00)
Behrouz Pashaee (KSC-NEM50)
Jim Broughton (KSC-NEM50)
Don Harris (MSFC-ER41)
Curt Larsen (JSC-C104) [NESC]
Alden Mackey (JSC-EA) [NESC/ATK Space Systems]
Ken Hamm (ARC-RE)
Tom Irvine (Dynamic Concepts, Inc.) [NESC Technical Discipline Team]
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Loads and Structural Dynamics
Requirements for Spaceflight
Hardware
Loads and Structural Dynamics Branch,
Structural Engineering Division,
Engineering Directorate

January 2011

National Aeronautics and
Space Administration

Lyndon B. Johnson Space Center
Houston, Texas
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Loads and Structural Dynamics Requirements for
Spaceflight Hardware

January 19, 2011

Prepared By:

/s/ Kenneth Schultz
K. P. Schultz
Loads and Structural Dynamics Branch
Lyndon B. Johnson Space Center

Approved By:

/s/ T. Scott West
T. S. West
Branch Chief, Loads and Structural Dynamics Branch
Lyndon B. Johnson Space Center

Approved By:

/s/ Edgar O. Castro
E. O. Castro
Division Chief, Structural Engineering Division
Lyndon B. Johnson Space Center

National Aeronautics and Space Administration
Lyndon B. Johnson Space Center
Houston, Texas

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REVISION HISTORY AND CHANGE LOG

Revision CHANGE DESCRIPTION DATE PAGES AFFECTED
NO.
RFI Release 1 (Initial version of document to
-- -- support RFI release of Commercial Crew 4/28/2010 All
Transportation Request for Information)
Baseline release of document to support
January 2011 RFI. Changes include:
- Modification of front matter, including
Purpose and Roles and Responsibilities
sections
- Identification of three additional reference
documents
- Addition of separate definition of and
requirements for sine vibration maximum
predicted environment
- Addition of requirement for crash safety
Baseline 1 1/17/2011 All
load factors for winged or lifting-body vehicles
- Significant reduction in the number and
specificity of requirements via deletion,
consolidation, and relocation of detail to the
Guidelines in Appendix B. Remaining set of
requirements were completely renumbered
- General correction of typographical and/or
grammatical errors
- Deletion of contents of Appendix C, since
adherence to SSP-50808 was added as a
program requirement

Note: Dates reflect latest signature date of Revision.

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FOREWORD

This document represents the collaborative effort of numerous individuals across many
NASA centers. In particular, the experience and expertise of the teams that developed
NASA-STD-5002 and the requirements and criteria documents for the Space Shuttle
Program, the International Space Station Program, and the Constellation Program was
relied on very heavily. Most, if not all, of the technical content in the current document
was either adapted from or directly incorporated from those previous documents. The
significant efforts expended in developing the Constellation Program Loads Control
Plan, CxP-70137, were instrumental to the creation of this document.

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TABLE OF CONTENTS
SECTION PAGE
1.0 INTRODUCTION ................................................................................................... 1
1.1 PURPOSE ............................................................................................................. 1
1.2 SCOPE .................................................................................................................. 1
1.3 APPLICABILITY .................................................................................................... 2
1.4 ROLES AND RESPONSIBILITIES ........................................................................ 2
1.5 IMPLEMENTATION ............................................................................................... 3
1.6 CONVENTION ...................................................................................................... 3
2.0 DOCUMENTS ....................................................................................................... 4
2.1 APPLICABLE DOCUMENTS ................................................................................. 4
2.2 REFERENCE DOCUMENTS ................................................................................. 4
2.3 ORDER OF PRECEDENCE .................................................................................. 5
3.0 DEFINITIONS ........................................................................................................ 5
4.0 LOADS REQUIREMENTS ..................................................................................... 8
4.1 GENERAL REQUIREMENTS ................................................................................ 8
4.1.1 Scope of Assessment ............................................................................. 8
4.1.2 Statistical Enclosure for Primary Structure Design Limit Loads ............... 9
4.1.3 Combining Low Frequency and Random Loads for Components and
Attachments ............................................................................................ 9
4.1.4 Loads Analysis Cycles .......................................................................... 10
4.1.5 Environments ........................................................................................ 11
4.1.6 Fatigue Loads Spectra Development .................................................... 14
4.1.7 Consideration of Gapping at Interfaces ................................................. 14
4.2 LAUNCH VEHICLE REQUIREMENTS ................................................................ 14
4.2.1 Mission Phase Analysis Responsibilities ............................................... 14
4.2.2 Development of Spacecraft Separation Initial Conditions ...................... 15
4.2.3 Development of Spacecraft Separation Initial Conditions for Aborts ...... 15
4.3 SPACECRAFT REQUIREMENTS ....................................................................... 16
4.3.1 Mission Phase Analysis Responsibilities ............................................... 16
4.3.2 Requirements for Specific Analyses ...................................................... 18
4.3.3 Spacecraft/Crew Interface Loads Requirements ................................... 21
4.3.4 Spacecraft Requirements for Joint Operations with ISS ........................ 22
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5.0 MODEL, FORCING FUNCTION AND DATA REQUIREMENTS .......................... 22
5.1 MATH MODEL REQUIREMENTS ....................................................................... 22
5.1.1 Coverage .............................................................................................. 22
5.1.2 Models for Coupled Loads Analysis ...................................................... 23
5.1.3 Damping ............................................................................................... 24
5.1.4 Data Recovery ...................................................................................... 25
5.1.5 Load Indicators ..................................................................................... 25
5.1.6 Load Indicator Redlines ........................................................................ 25
5.1.7 Model Verification ................................................................................. 26
5.1.8 ISS-imposed Model Requirements........................................................ 27
5.2 DATA TRANSFER REQUIREMENTS ................................................................. 27
5.2.1 SCP Deliveries ...................................................................................... 28
5.2.2 LVP Deliveries ...................................................................................... 29
6.0 DYNAMIC COUPLING REQUIREMENTS ........................................................... 29
6.1 AEROELASTICITY .............................................................................................. 30
6.2 STATIC AEROELASTICITY ................................................................................ 30
6.2.1 Divergence ........................................................................................... 30
6.2.2 Control System Reversal ...................................................................... 31
6.3 DYNAMIC AEROELASTICITY ............................................................................. 31
6.3.1 Flutter ................................................................................................... 31
6.3.2 Panel Flutter ......................................................................................... 32
6.3.3 Stall Flutter ........................................................................................... 32
6.3.4 Control Surface Buzz ............................................................................ 33
6.4 INTERACTIONS BETWEEN VEHICLE FLIGHT CONTROL SYSTEM AND
ELASTIC MODES ............................................................................................... 34
6.5 POGO DESIGN AND ANALYSIS REQUIREMENTS ........................................... 34
6.6 SLOSH ................................................................................................................ 35
LIST OF TABLES
TABLE 4.2.3 ABORT SCENARIOS ....................................................................................... 15
TABLE 4.3.2.2.5-1 CRASH SAFETY LOAD FACTORS FOR HORIZONTAL LANDING ....... 21
APPENDICES
APPENDIX A ACRONYMS AND ABBREVIATIONS ............................................................. A-1
APPENDIX B GUIDELINES FOR LOADS ANALYSIS OF SPECIFIC FLIGHT PHASES ...... B-1
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APPENDIX C <DELETED> ................................................................................................... C-1
APPENDIX D MODEL-RELATED REQUIREMENTS FROM THE SPACE STATION LOADS
CONTROL PLAN ................................................................................................ D-1

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1.0 INTRODUCTION
1.1 PURPOSE
The purpose of this document is to establish requirements relating to the loads and
structural dynamics technical discipline for NASA and commercial spaceflight launch
vehicle and spacecraft hardware. Requirements are defined for the development of
structural design loads and recommendations regarding methodologies and practices
for the conduct of load analyses are provided. As such, this document represents an
implementation of NASA STD-5002. Requirements are also defined for structural
mathematical model development and verification to ensure sufficient accuracy of
predicted responses. Finally, requirements for model/data delivery and exchange are
specified to facilitate interactions between Launch Vehicle Providers (LVPs), Spacecraft
Providers (SCPs), and the NASA Technical Authority (TA) providing insight/oversight
and serving in the Independent Verification and Validation role.
In addition to the analysis-related requirements described above, a set of requirements
are established concerning coupling phenomena or other interaction between structural
dynamics and aerodynamic environments or control or propulsion system elements.
Such requirements may reasonably be considered structure or control system design
criteria, since good engineering practice dictates consideration of and/or elimination of
the identified conditions in the development of those subsystems. The requirements are
included here, however, to ensure that such considerations are captured in the design
space for launch vehicles (LV), spacecraft (SC) and the Launch Abort Vehicle (LAV).
The requirements in this document are focused on analyses to be performed to develop
data needed to support structural verification. As described in JSC 65828, Structural
Design Requirements and Factors of Safety for Spaceflight Hardware, implementation
of the structural verification requirements is expected to be described in a Structural
Verification Plan (SVP), which should describe the verification of each structural item for
the applicable requirements. The requirement for and expected contents of the SVP
are defined in JSC 65828. The SVP may also document unique verifications that meet
or exceed these requirements with Technical Authority approval.
1.2 SCOPE
This document includes requirements governing
a. the analytical approaches and criteria for the development of structural design
loads, and environments (natural and induced), including vehicle loads,
acoustics, and buffet,
b. the verification approach applicable to the mathematical models used for loads
development,
c. the transfer of models and forcing functions, environments, and results data
among various stakeholders (LVP, SCP, and NASA),
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d. the roles and responsibilities for loads development, including general task
descriptions and input and output requirements, and
e. the considerations of phenomena associated with the interaction of system
structural dynamics and environments and vehicle subsystems.
This document is intended to cover analyses representing all phases of a spaceflight
vehicle mission profile, including pre-flight, post-flight, and abort activities. The
requirements herein represent the minimum set of conditions necessary to ensure
proper identification of bounding loads and loading conditions and, in turn, contribute to
a structural design solution which is adequate to maintain structural integrity and the
required degree of functionality during all phases of the expected life cycle.
1.3 APPLICABILITY
This document establishes requirements for the loads and dynamics technical discipline
and provides guidelines and good design practices identified by the NASA loads and
dynamics technical community. It is applicable to both NASA and commercial launch
vehicles and spacecraft. This document contains requirements that LVPs and SCPs
can choose to either adopt as written or propose an alternate. LVPs and SCPs are
allowed to propose alternate requirements and standards that they consider to meet or
exceed the requirements listed herein.
The NASA Program under which the launch vehicle and/or spacecraft is developed will
charter a Loads and Structures Panel (LSP) for reviewing and approving the
implementation of the requirements of this document. The LSP will serve as the
responsible Technical Authority for structural design limit loads and environments. The
Technical Authority will evaluate the equivalency of any alternate requirements
proposed by the LVPs and SCPs. It will be the responsibility of the LVP and/or SCP to
demonstrate to the NASA TA that a proposed alternate requirement fully meets the
intent of the requirements of this document and to obtain formal NASA approval of the
alternate requirement(s). When consensus cannot be reached on the resolution of an
issue, the TA will bring forward the issue with a recommendation to the appropriate
Program Board, along with the organizational team members presenting their conflicting
positions.
1.4 ROLES AND RESPONSIBILITIES
Depending on mission phase, responsibility for performing loads analysis may fall to
either the LVP, the SCP, or both. For example, if the LVP is responsible for ascent
atmospheric flight analyses, the LVP will require structural dynamic math models from
the SCP to complete the analysis, while resulting induced aeroacoustic and vibration
environments and LV/SC interface load states will be required by the SCP to perform
detailed assessment of the responses of SC internal components. In such cases, timely
transfer of model, forcing function, and environment data is crucial to continued
progress of design efforts. Note that the possibility exists that the LVP and the SCP are
the same commercial entity.
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